The main method for producing monocyclic ketones is the liquid-phase oxidation of corresponding cycloalkanes with atmospheric oxygen, which oxidation can be carried out in the presence of a catalyst and without it. In both cases, the reaction products formed are represented by a mixture of cyclic ketones and alcohols. For example, while oxidizing cyclododecanes at a temperature comprised between 155 and 170° and a pressure of between 1 and 10 atm, in the presence of boric acid, a mixture of cyclododecanones and cyclododecanols is formed having an ultimate selectivity of about 90%, an obtainable conversion between 5 and 20%/U.S. Pat. No 3,419,615 CO7C 29/52, 1968/ and, along with this, a selectivity involving the ketone does not exceed 20%. The oxidation of cyclododecanes into a mixture of cyclododecanones and cyclododecanols can likewise be carried out with employment, as catalysts, of Co or Mn salts at a temperature comprised between 90 and 150°/GB Pat. No 930842, CO7C, 1963/. In patent U.S. Pat. No 3,917,708, CO7C 29/50, 1975 there is shown and described a method for oxidizing cyclic alkanes C5–C12 into a mixture of corresponding cyclic ketones and alcohols, in the presence of Co, Mn, Cu, Fe, Ni salts. The process is conducted at 130–160° C., a pressure of between 5 and 25 atm and a conversion of between 3 and 6%.
The common defect of these methods is formation, alongside ketones, of appreciable amounts of cyclic alcohols and also a drastic reduction in a reaction selectivity, as the conversion is increased.
In patent GB No 649680, CO7C 45/34, 1951, a disclosure is made of a method for oxidizing olefins into carbonyl compounds with nitrous oxide. According to this method, it is particularly possible to obtain cyclooctanones by the oxidation of cyclooctenes. This method is disadvantageous in low selectivity and stringent reaction conditions.
A second serious disadvantage of this method is a possibility of ignitable mixtures being formed. For explosion hazard to be precluded, the authors of the patent propose adding further saturated hydrocarbons to a reaction mixture. However, as shown by later research work, the mixtures of saturated hydrocarbons with N2O are nearly as much dangerously explosive as those of olefins /G. Panetier, A. Sicard, V Symposium on Combustion, 620, 1955; B. B. Brandt, L. A. Matov, A. I. Rozlovsky, V. S. Khailov, Khim. Prom. 1960, No 5, pp. 67–73/. Therefore, the saturated hydrocarbons, despite their lesser reactivity, cannot be a means for precluding the explosion hazard.